Flammable propellants in plastic aerosols

ABSTRACT

Plastic aerosol containers larger than 4 ounces can safely contain flammable, liquefied gas propellants when the complete aerosol device takes safety attributes of the plastic aerosol container and the complete aerosol product, rather than relying on the separate attributes of the aerosol composition and the propellant only.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the safe use of flammable propellants with plastic aerosol containers.

2. Description of the Related Art

Pressurized containers for dispensing aerosols are well known in the art, and are typically constructed of metal in order to withstand the inherent internal pressure of aerosols. However, it is desirable to provide a plastic container capable of withstanding the internal pressures generated by an aerosol because plastic has many advantages over metal. Some of these advantages include the ease and economy of manufacture, and aesthetic appeal to an end user. However, flammable propellants, commonly used in metal aerosol containers, are not currently used in plastic aerosol containers because of safety concerns. Instead, non-flammable compressed gases, such as carbon dioxide, are used.

However, compressed gas propellants have limitations for aerosol use, as suggested in U.S. Pat. App. 2005/0242101 to Skalitzky. Pressure in the aerosol container is proportional to the amount of compressed gas propellant (unlike liquified gas propellants which maintain constant pressure) so the amount of propellant that can be used is limited. Also, compressed gas propellants permeate through plastic containers. The low usage level and permeation combine to limit the shelf life of the aerosol and may require upgraded resin or other costly bottle enhancements to have an acceptable shelf life. Finally, with compressed gas propellant, the pressure in the aerosol container drops as the product is used. This results in changing spray performance as the product is used and limits the utility of plastic aerosol containers using compressed gas propellants.

The problems with compressed gas propellants can be avoided by using liquified gas propellants. However, the preferred liquified gas propellants (such as hydrocarbons, dimethyl ether and HFC 152a) are flammable under hazardous regulations such as 49 CFR § 173.115(a), and are not allowed even under current special permits because of safety concerns.

To overcome these problems of prior art plastic aerosol products, aerosols of the present invention are formulated based on the safety attributes of the complete aerosol device, rather than relying on the safety attributes of the aerosol composition and the propellant.

SUMMARY OF THE INVENTION

In accordance with the above objects and those that will be mentioned and will become apparent below, one aspect of the present invention comprises an aerosol device comprising:

-   -   a. a plastic aerosol container having an actuator, a valve, and         containing an aerosol product composition comprising:         -   i. an aqueous composition;         -   ii. a flammable, liquefied gas propellant;     -   b. wherein the container has a capacity of more than 4 fluid         ounces and less than 1 liter;     -   c. wherein the combination of said composition and said         propellant has a chemical heat of combustion not exceeding 20         kJ/g;     -   d. wherein the plastic container has a minimum burst pressure of         210 psig;     -   e. wherein the pressure inside the plastic container is no more         than 150 psig at 130° F.;     -   f. wherein the aerosol device has a spray distance of 15 cm or         greater; and     -   g. wherein the aerosol device does not ignite at a distance of         15 cm between a burner flame and the actuator.

In accordance with the above objects and those that will be mentioned and will become apparent below, another aspect of the present invention comprises an aerosol device comprising:

-   -   a. a plastic aerosol container having an actuator, a valve, and         containing an aerosol product composition comprising:         -   i. an aqueous composition;         -   ii. a flammable, liquefied gas propellant;     -   b. wherein the combination of said composition and said         propellant has a chemical heat of combustion not exceeding 20         kJ/g;     -   c. wherein the aerosol device has a spray distance of 15 cm or         greater; and     -   d. wherein the aerosol device does not ignite at a distance of         15 cm between a burner flame and the actuator.

In accordance with the above objects and those that will be mentioned and will become apparent below, another aspect of the present invention comprises an aerosol device comprising:

-   -   a. a plastic aerosol container having an actuator, a valve, and         containing an aerosol product composition comprising:         -   i. an aerosol composition;         -   ii. a flammable, liquefied gas propellant;     -   b. wherein the plastic container has a minimum burst pressure of         210 psig;     -   c. wherein the combination of said composition and said         propellant has a chemical heat of combustion not exceeding 20         kJ/g;     -   d. wherein the aerosol device has a spray distance of 15 cm or         greater; and     -   e. wherein the aerosol device does not ignite at a distance of         15 cm between a burner flame and the actuator.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified systems or process parameters that may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to limit the scope of the invention in any manner.

All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference.

As used herein and in the claims, the term “comprising” is inclusive or open-ended and does not exclude additional unrecited elements, compositional components, or method steps. Accordingly, the term “comprising” encompasses the more restrictive terms “consisting essentially of” and “consisting of”.

It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a “surfactant” includes two or more such surfactants.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

In the application, effective amounts are generally those amounts listed as the ranges or levels of ingredients in the descriptions, which follow hereto. Unless otherwise stated, amounts listed in percentage (“%'s”) are in weight percent (based on 100% active) of the cleaning composition alone.

The term “surfactant”, as used herein, is meant to mean and include a substance or compound that reduces surface tension when dissolved in water or water solutions, or that reduces interfacial tension between two liquids, or between a liquid and a solid. The term “surfactant” thus includes anionic, nonionic, cationic and/or amphoteric agents.

The aerosol composition can be used as a disinfectant, sanitizer, and/or sterilizer. As used herein, the term “disinfect” shall mean the elimination of many or all pathogenic microorganisms on surfaces with the exception of bacterial endospores. As used herein, the term “sanitize” shall mean the reduction of contaminants in the inanimate environment to levels considered safe according to public health ordinance, or that reduces the bacterial population by significant numbers where public health requirements have not been established. An at least 99% reduction in bacterial population within a 24 hour time period is deemed “significant.” As used herein, the term “sterilize” shall mean the complete elimination or destruction of all forms of microbial life and which is authorized under the applicable regulatory laws to make legal claims as a “Sterilant” or to have sterilizing properties or qualities.

As used herein, the term “polymer” generally includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the molecule. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries.

The term “aerosol” will be understood herein to encompass both aerosols, literally, and other liquid or flowable products that can be dispensed from pressurized containers in a manner comparable to aerosolized products. Such products include but are not limited to foamed or gel preparations or to liquid products delivered in a non-aerosol stream. It is also herein contemplated that the present invention may be practiced in many consumer products including, but not limited to, cleaners, disinfectants, antiperspirants, deodorants, hairsprays, cooking sprays, beverages, perfumes, shaving creams/gels, or drug products.

The term “aerosol composition” as used herein means any composition that is pressurized from a gas and/or liquefied gas propellant, wherein the propellant provides a way for pushing or moving the composition to and/or through an application device. These aerosol products can deliver the composition to its targeted source (e.g., hard surface, air, consumers skin, hair, underarm, etc.) in various ways including, but not limited to, a spray or via a porous application surface.

The term “plastic” is defined herein as any polymeric material that is capable of being shaped or molded, with or without the application of heat. Usually plastics are a homo-polymer or co-polymer that of high molecular weight. Plastics fitting this definition include, but are not limited to, polyolefins, polyesters, nylon, vinyl, acrylic, polycarbonates, polystyrene, and polyurethane.

The term “plastic aerosol container” refers to the non-refillable container vessel of the pressurized package being made substantially of plastic and fitted with a sealing valve and actuator. The sealing valve and actuator of the package may or may not necessarily be made substantially of plastic.

The term “pressurized plastic container” or “pressurized plastic package” is defined herein as a container with contents, where the contents have a pressure of at least 10 PSI greater than atmospheric pressure at 25° C.

The term “flammable, liquefied gas propellant” is defined herein as a material that is a liquid at 20° C. under 164.7 psia of pressure and a gas at 20° C. or less and 14.7 psia of pressure, which (1) is ignitable at 14.7 psia when in a mixture of 13 percent or less by volume with air; or (2) has a flammable range at 14.7 psia with air of at least 12 percent regardless of the lower limit.

Propellant

Several types of propellants are used to pressurize the container of the present invention. These materials include flammable, liquefied propellants. Flammable, liquefied propellants of the present invention include, but are not limited to, butane, isobutane, propane, dimethyl ether, 1,1-difluoroethane and mixtures thereof.

Suitable liquefied propellants include C1-C6 alkyl ethers, C3-C6 hydrocarbons, halocarbons and mixtures thereof. Suitable hydrocarbons include n-butane, isobutane, isobutane/propane mixtures all of which are available from the Phillips Petroleum Company under the respective trademarks A17, A31, A46 and A70. Among the alkyl ethers, more prominent is dimethyl ether, diethyl ether, methylethyl ether and diisopropyl ether. Most preferred is dimethyl ether. Halocarbons can include dichlorodifluoromethane, dichlorotetrafluoroethane, chlorotrifluoromethane and mixtures thereof. Amounts of flammable, liquefied propellant may range from about 1 to about 80%, or from about 2 to about 50%, or from about 5 and about 20% by weight based on the aerosol composition and propellant combination.

Aerosol Composition

The aerosol composition may contain one or more surfactants selected from nonionic, anionic, cationic, ampholytic, amphoteric and zwitterionic surfactants and mixtures thereof. A typical listing of nonionic, anionic, ampholytic, and zwitterionic classes, and species of these surfactants, is given in U.S. Pat. No. 3,929,678 to Laughlin and Heuring. A list of suitable cationic surfactants is given in U.S. Pat. No. 4,259,217 to Murphy. The surfactants may be present at a level of from about 0% to 90%, or from about 0.001%

Suitable organic solvents include, but are not limited to, C₁₋₆ alkanols, C₁₋₆ diols, C₁₋₁₀ alkyl ethers of alkylene glycols, C₃₋₂₄ alkylene glycol ethers, polyalkylene glycols, short chain carboxylic acids, short chain esters, isoparafinic hydrocarbons, mineral spirits, alkylaromatics, terpenes, terpene derivatives, terpenoids, terpenoid derivatives, formaldehyde, and pyrrolidones. Alkanols include, but are not limited to, methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, and hexanol, and isomers thereof. Diols include, but are not limited to, methylene, ethylene, propylene and butylene glycols. Alkylene glycol ethers include, but are not limited to, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol n-propyl ether, propylene glycol monobutyl ether, propylene glycol t-butyl ether, di- or tri-polypropylene glycol methyl or ethyl or propyl or butyl ether, acetate and propionate esters of glycol ethers. Short chain carboxylic acids include, but are not limited to, acetic acid, glycolic acid, lactic acid and propionic acid. Short chain esters include, but are not limited to, glycol acetate, and cyclic or linear volatile methylsiloxanes. Water insoluble solvents such as isoparafinic hydrocarbons, mineral spirits, alkylaromatics, terpenoids, terpenoid derivatives, terpenes, and terpenes derivatives can be mixed with a water-soluble solvent when employed. The solvents can be present at a level of from 0.001% to 10%, or from 0.01% to 10%, or from 1% to 4% by weight.

The aerosol compositions optionally contain one or more of the following adjuncts: stain and soil repellants, lubricants, odor control agents, perfumes, fragrances and fragrance release agents, and bleaching agents. Other adjuncts include, but are not limited to, acids, electrolytes, dyes and/or colorants, solubilizing materials, stabilizers, thickeners, defoamers, hydrotropes, cloud point modifiers, preservatives, and other polymers. The solubilizing materials, when used, include, but are not limited to, hydrotropes (e.g. water soluble salts of low molecular weight organic acids such as the sodium and/or potassium salts of toluene, cumene, and xylene sulfonic acid). The acids, when used, include, but are not limited to, organic hydroxy acids, citric acids, keto acid, and the like. Electrolytes, when used, include, calcium, sodium and potassium chloride. Thickeners, when used, include, but are not limited to, polyacrylic acid, xanthan gum, calcium carbonate, aluminum oxide, alginates, guar gum, methyl, ethyl, clays, and/or propyl hydroxycelluloses. Defoamers, when used, include, but are not limited to, silicones, aminosilicones, silicone blends, and/or silicone/hydrocarbon blends. Bleaching agents, when used, include, but are not limited to, peracids, hypohalite sources, hydrogen peroxide, and/or sources of hydrogen peroxide.

Preservatives, when used, include, but are not limited to, mildewstat or bacteriostat, methyl, ethyl and propyl parabens, short chain organic acids (e.g. acetic, lactic and/or glycolic acids), bisguanidine compounds (e.g. Dantagard® and/or Glydant®) and/or short chain alcohols (e.g. ethanol and/or IPA). The mildewstat or bacteriostat includes, but is not limited to, mildewstats (including non-isothiazolone compounds) include Kathon GC®, a 5-chloro-2-methyl-4-isothiazolin-3-one, KATHON ICP®, a 2-methyl-4-isothiazolin-3-one, and a blend thereof, and KATHON 886®, a 5-chloro-2-methyl-4-isothiazolin-3-one, all available from Rohm and Haas Company; BRONOPOL®, a 2-bromo-2-nitropropane 1, 3 diol, from Boots Company Ltd., PROXEL CRL®, a propyl-p-hydroxybenzoate, from ICI PLC; NIPASOL M®, an o-phenyl-phenol, Na⁺ salt, from Nipa Laboratories Ltd., DOWICIDE A®, a 1,2-Benzoisothiazolin-3-one, from Dow Chemical Co., and IRGASAN DP 200®, a 2,4,4′-trichloro-2-hydroxydiphenylether, from Ciba-Geigy A.G.

The aerosol composition may include antimicrobial agents for purposes of disinfection, sanitization, sterilization, or microbiological control. Antimicrobial agents, include carboxylic acids, such as 2-hydroxycarboxylic acids, quaternary ammonium compounds, metal salts and phenolics. Non-limiting examples of these quaternary compounds include benzalkonium chlorides and/or substituted benzalkonium chlorides, di(C₆-C₁₄)alkyl di-short chain (C₁₋₄ alkyl and/or hydroxyalkl) quaternaryammonium salts, N-(3-chloroallyl) hexaminium chlorides, benzethonium chloride, methylbenzethonium chloride, and cetylpyridinium chloride. Other quaternary compounds include the group consisting of dialkyldimethyl ammonium chlorides, alkyl dimethylbenzylammonium chlorides, dialkylmethyl-benzylammonium chlorides, and mixtures thereof. Biguanide antimicrobial actives including, but not limited to polyhexamethylene biguanide hydrochloride, p-chlorophenyl biguanide; 4-chlorobenzhydryl biguanide, halogenated hexidine such as, but not limited to, chlorhexidine (1,1′-hexamethylene-bis-5-(4-chlorophenyl biguanide) and its salts are also in this class.

The aerosol composition may include a builder or buffer, which increase the effectiveness of the surfactant. The builder or buffer can also function as a softener and/or a sequestering agent in the cleaning composition. A variety of builders or buffers can be used and they include, but are not limited to, phosphate-silicate compounds, zeolites, alkali metal, ammonium and substituted ammonium poly-etates, trialkali salts of nitrilotriacetic acid, carboxylates, polycarboxylates, carbonates, bicarbonates, polyphosphates, aminopolycarboxylates, polyhydroxy-sulfonates, and starch derivatives. Builders or buffers can also include polyacetates and polycarboxylates. The polyacetate and polycarboxylate compounds include, but are not limited to, sodium, potassium, lithium, ammonium, and substituted ammonium salts of ethylenediamine tetraacetic acid, ethylenediamine triacetic acid, ethylenediamine tetrapropionic acid, diethylenetriamine pentaacetic acid, nitrilotriacetic acid, oxydisuccinic acid, iminodisuccinic acid, mellitic acid, polyacrylic acid or polymethacrylic acid and copolymers, benzene polycarboxylic acids, gluconic acid, sulfamic acid, oxalic acid, phosphoric acid, phosphonic acid, organic phosphonic acids, acetic acid, and citric acid. These builders or buffers can also exist either partially or totally in the hydrogen ion form. The builder agent can include sodium and/or potassium salts of EDTA and substituted ammonium salts. The substituted ammonium salts include, but are not limited to, ammonium salts of methylamine, dimethylamine, butylamine, butylenediamine, propylamine, triethylamine, trimethylamine, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, ethylenediamine tetraacetic acid and propanolamine. Buffering and pH adjusting agents, when used, include, but are not limited to, organic acids, mineral acids, alkali metal and alkaline earth salts of silicate, metasilicate, polysilicate, borate, hydroxide, carbonate, carbamate, phosphate, polyphosphate, pyrophosphates, triphosphates, tetraphosphates, ammonia, hydroxide, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, triethanolamine, and 2-amino-2methylpropanol. Preferred buffering agents for compositions of this invention are nitrogen-containing materials. Some examples are amino acids such as lysine or lower alcohol amines like mono-, di-, and tri-ethanolamine. Other preferred nitrogen-containing buffering agents are tri(hydroxymethyl)amino methane (TRIS), 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-propanol, 2-amino-2-methyl-1,3-propanol, disodium glutamate, N-methyl diethanolamide, 2-dimethylamino-2-methylpropanol (DMAMP), 1,3-bis(methylamine)-cyclohexane, 1,3-diamino-propanol N,N′-tetra-methyl-1,3-diamino-2-propanol, N,N-bis(2-hydroxyethyl)glycine (bicine) and N-tris(hydroxymethyl)methyl glycine (tricine). Other suitable buffers include ammonium carbamate, citric acid, acetic acid. Mixtures of any of the above are also acceptable. Useful inorganic buffers/alkalinity sources include ammonia, the alkali metal carbonates and alkali metal phosphates, e.g., sodium carbonate, sodium polyphosphate. For additional buffers see WO 95/07971, which is incorporated herein by reference. Other suitable pH adjusting agents include sodium or potassium hydroxide. When employed, the builder, buffer, or pH adjusting agent comprises at least about 0.001% and typically about 0.01-5% of the aerosol composition. Suitably, the builder or buffer content is about 0.01-2%.

In one embodiment, the compositions comprise hypohalite, defined as hypohalous acid and/or salts thereof. Suitable hypohalous acids and salts may be provided by a variety of sources, including compositions that lead to the formation of positive halide ions and/or hypohalite ions, as well as compositions that are organic based sources of halides, such as chloroisocyanurates, haloamines, haloimines, haloimides and haloamides, or mixtures thereof. These compositions may also produce hypohalous acid or hypohalite species in situ. Suitable hypohalous acids and salts for use herein include the alkali metal and alkaline earth metal hypochlorites, hypobromites, hypoiodites, chlorinated trisodium phosphate dodecahydrates, potassium and sodium dichloroisocyanurates, potassium and sodium trichlorocyanurates, N-chloroimides, N-chloroamides, N-chlorosulfamide, N-chloroamines, chlorohydantoins such as dichlorodimethyl hydantoin and chlorobromo dimethylhydantoin, bromo-compounds corresponding to the chloro-compounds above, and compositions which generate the corresponding hypohalous acids, or mixtures thereof.

In one embodiment wherein the compositions herein are liquid, said hypohalite compositions is an alkali metal and/or alkaline earth metal hypochlorite, or mixtures thereof. Compositions may be an alkali metal and/or alkaline earth metal hypochlorite selected from the group consisting of sodium hypochlorite, potassium hypochlorite, magnesium hypochlorite, lithium hypochlorite and calcium hypochlorite, and mixtures thereof. The hypohalous acids and salt composition may be an equilibrium mixture of hypochlorous acid and sodium hypochlorite. The active species is present in an amount from above zero to about 15 weight percent of the composition, or from about 0.001 weight percent (10 ppm) to about 10 weight percent of the composition, or from about 0.005 (50 ppm) to about 5 weight percent of the composition, or from about 0.005 (50 ppm) to about 0.02 (200 ppm) weight percent of the composition.

The aerosol composition may be aqueous or nonaqueous. When the aerosol composition is an aqueous composition, water can be, along with the solvent, a predominant ingredient. The water can be present at a level of less than 99.9%, or less than about 99%, or less than about 98%. Additionally, the water can be present at a level of greater than 5%, or greater than 50%. Deionized water is preferred.

Plastic Aerosol Containers

Plastic aerosol containers are described in U.S. Pat. App. 2004/0149781 to Kunesh et al., U.S. Pat. App. 2005/0060953 to Altonen et al., 2005/0218164, U.S. Pat. App. 2003/0215400 to Schroeder et al., U.S. Pat. No. 6,390,326 to Hung, U.S. Pat. No. 5,152,411 to Pope et al., U.S. Pat. No. 6,491,187 to Walters, U.S. Pat. App. 2003/0215399 to Smith, U.S. Pat. No. 5,553,753 to Abplanalp, U.S. Pat. No. 5,199,615 to Downing et al., all of which are incorporated by reference. The thermoplastic materials, which can be used, are generally polymers such as polyethylene (PE) or polyethylene terephthalates (PET), polyethylene glycol terephthalates or polypropylene (PP). Polyamide (PA) or ethylenevinyl alcohol (EVOH) can be used for possible further layers situated between the inner or outer edge layers. However, it is also possible to use any other plastics which are melt processable. Suitable containers can be produced from physical PET/PEN resin blends, polyethylene naphthalene (PEN) copolymers, or PEN homopolymers. Suitable containers have a capacity of greater than 4 fluid ounces, or greater than 10 fluid ounces, or greater than 20 fluid ounces, or less than 1 liter. Nozzles for the aerosols may be regulated by valves, such as those available from the Precision Valve Company.

The burst pressure (or failure pressure) of the body of the container is typically supplied by the manufacturer of the container as determined during standard testing of the container during manufacture. The minimum burst pressure is suitably greater than 100 psig, or greater than 150 psig, or greater than 200 psig, or at least 210 psig. The pressure inside the aerosol container is suitably no greater than 100 psig at 130° F., or 125 psig at 130° F., or 150 psig at 130° F., or 180 psig at 130° F. The pressure inside the aerosol container is suitably greater than 25 psi at 70° F., or greater than 50 psi at 70° F., or greater than 75 psi at 70° F.

Department of Transportation (DOT) Regulations

Aerosol products can be highly flammable and can create a substantial fire hazard during storage. In a fire, aerosol canisters can rupture or BLEVE (boiling liquid expanding vapor explosion) and release flammable components such as propellant, solvents, or other flammable compounds, which can then be ignited by the fire thus resulting in further spreading of the flames. Furthermore, some aerosol products when exposed to fire have been known to rupture and “rocket with trailing burning liquid” away from their original position and spread the fire to previously unaffected areas.

Typically, aerosol products are contained in metal canisters made of aluminum or tin plate. These canisters have good mechanical strength and heat resistance that significantly reduce the fire hazard by providing a substantial barrier between the product and fire. Metal canisters are often capable of containing products with pressures as high as several hundred PSI so the temperature at which the canister fails and BLEVE occurs can be quite high. Moreover the metals that these canisters are composed of typically have melt temperatures that are greater than 400° C.; therefore, they are not subject to failure due to melting at relatively low fire temperatures (below 200° C.).

Plastic aerosol containers generally have both poorer mechanical strength and poorer heat resistance compared to metal containers. Plastic aerosol containers larger than 4 fl. oz. are not authorized, according to DOT regulations under 49 CFR § 173.306(a). The Special Permits have been approved (DOT-E13292, DOT-E14097 and DOT-SP14205) to supercede regulations, but they require that both the aerosol composition and the propellant are non-hazardous. From a practical standpoint, this limits these products to using compressed gas propellants such as carbon dioxide and nitrogen, which are Division 2.2 non-flammable, non-poisonous gases under 49 CFR § 173.115(b).

Plastic aerosol containers must also undergo additional testing. For example, the Department of Transportation (DOT) specifies that each package filled with a flammable gas must be subjected to a 130° Fahrenheit environment (referred to as “hot tanking”) prior to shipment in accordance with DOT 49 CFR Ch. 1 [10-1-10], section Research and Special Programs Administration. These additional testing requirements significantly increase plastic aerosol container functional testing and the ability of plastic aerosol containers to be brought to market. This additional testing also worsens the stability of the pressurized plastic package due to increased temperatures that reduce the mechanical strength of the plastic and increase the pressure within the package.

National Fire Protection Association Code

The fire hazard of an aerosol product can be shown by its hazard category, as defined the National Fire Protection Association NFPA 30B (Code for the Manufacture and Storage of Aerosol Products 2002 Edition), and is hereby incorporated by reference). This Code severely restricts plastic aerosol containers to a maximum size of 4 fl. oz. and defines their hazard category based on the product heat of combustion. The definition of a suitable aerosol container is defined in NFPA 30B Section 3.3.2 as a metal can, up to a maximum size of 1000 ml (33.8 fl. oz.), or a glass or plastic bottle, up to a maximum size of 118 ml (4 fl. oz.), that is designed and intended to dispense an aerosol composition. For suitable aerosol containers by the definition above, hazard categories of Level 1, 2, and 3 are based on the amount and type of flammable material in the product. More specifically, if a product has a chemical heat of combustion that is from 0 to 8,600 Btu/lb (20 kJ/g), then the product is classified as a Level 1. Similarly, if a product has a chemical heat of combustion that is from 8,600 Btu/lb (20 kJ/g) to 13,000 Btu/lb (30 kJ/g), then the product is classified as a Level 2. Lastly, if a product has a chemical heat of combustion that is greater than 13,000 Btu/lb (30 kJ/g), then the product is classified as a Level 3.

The chemical heat of combustion can be calculated from the heat of combustion of the individual components. For a product that consists of a number of components, the chemical heat of combustion is the summation of the weighted heats of combustion for the individual components, as described in National Fire Protection Association NFPA 30B, Annex F.

The fire hazard classification of an aerosol product is used to determine proper storage conditions. These storage conditions include necessary sprinkler design, storage height, and secondary container. Level 1 products have the least stringent storage conditions. Level 2 and 3 products have storage requirements that are more commensurate with their increased risk. Level 3, having the most risk, has the most stringent and expensive requirements. These stringent storage conditions increase the cost and the complexity of merchandizing aerosol products. Storage regulations are described in detail in NFPA 30B.

UN Test Method for Determination of the Ignition Distance of a Spray Jet

The UN flame distance test (or Determination of the Ignition Distance of the Spray Jet) is described in UN/SCETDG/19/INF.34 Attachment 2 and is applicable for aerosol products with a spray distance of 15 cm or greater. Aerosol products with a spray distance of less than 15 cm such as: dispensing foams, mousses, gels or fitted with a metering valve, are excluded from this test. For an aerosol product to be non-flammable under this test, ignition of the aerosol spray cannot be obtained at 15 cm distance between the burner flame and the aerosol's actuator.

EXAMPLES

By focusing on the safety of the complete aerosol device, rather than the flammable propellant, a suitably safe plastic aerosol device can be manufactured. Several containers were tested for minimum burst pressure at 55° C. Containers having burst pressures of 163 psig and 197 psig were not satisfactory. A suitable device was tested having a capacity of 17.9 fl. oz. overflow volume, a minimum burst pressure of at least 245 psig, and an internal pressure of no more than 150 psig at 130° F.

Ignition Distance Flammability, Propellant, and Heat of Combustion

Samples containing flammable propellants were tested for flammability at 15 cm distance between a burner flame and the aerosol actuator in Table 1 below. The table shows that neither the flammable propellant concentration nor the heat of combustion of the entire compositions is a predictor of flammability by the UN flame distance test. The valve for all samples was SeaquistPerfect® sample no. 188739-XT91 with 0.018″ stem and 0.062″ body w/o vapor tap. The actuator for all of the tests reported below was XT-150 with 0.018″ DynaMist® insert—part number 0703-04450-18.

TABLE 1 % wt Ignition Distance Heat of Propellant Test Combustion kJ/g Formula 409 ®  5% A-46 Non-flammable 3 concentrate Formula 409 ® 10% A-46 Non-flammable 5 concentrate Formula 409 ® 20% A-46 Non-flammable 9 concentrate Formula 409 ® 30% A-46 Flammable 14 concentrate Water 20% A-31 Non-flammable 14 Water 44% DME Non-flammable 20.2

Ignition Distance Test and Actuator

The entire aerosol contents can be flammable or non-flammable depending upon the actuator used. An aqueous composition containing 20% A-46® propellant was flammable with a misting insert, but not flammable with a SolidPattern® 0.016″ insert, which provides a coarser spray and narrower pattern.

While this detailed description includes specific examples according to the invention, those skilled in the art will appreciate that there are many variations of these examples that would nevertheless fall within the general scope of the invention and for which protection is sought in the appended claims. 

1. An aerosol device comprising: a. a plastic aerosol container having an actuator, a valve, and containing an aerosol product composition comprising: i. an aqueous composition; ii. a flammable, liquefied gas propellant; b. wherein the plastic aerosol container has a capacity of more than 4 fluid ounces and less than 1 liter; c. wherein the combination of said aqueous composition and said propellant has a chemical heat of combustion not exceeding 20 kJ/g; d. wherein the plastic aerosol container has a minimum burst pressure of at least 210 psig; e. wherein the pressure inside the plastic aerosol container is no more than 150 psig at 130° F.; f. wherein the aerosol device has a spray distance of 15 cm or greater; and g. wherein the aerosol device does not ignite at a distance of 15 cm between a burner flame and the actuator.
 2. The aerosol device of claim 1; wherein the aqueous composition comprises greater than 5% water.
 3. The aerosol device of claim 1; wherein the aqueous composition comprises greater than 50% water.
 4. The aerosol device of claim 1; wherein the pressure inside the plastic aerosol container is greater than 25 psi at 70° F.
 5. The aerosol device of claim 1; wherein the pressure inside the plastic aerosol container is greater than 50 psi at 70° F.
 6. The aerosol device of claim 1; wherein the pressure inside the plastic aerosol container is greater than 75 psi at 70° F.
 7. The aerosol device of claim 1; wherein the propellant comprises a hydrocarbon.
 8. The aerosol device of claim 1; wherein the propellant comprises an alkyl ether.
 9. An aerosol device comprising: a. a plastic aerosol container having an actuator, a valve, and containing an aerosol product composition comprising: ii. an aqueous composition; iii. a flammable, liquefied gas propellant; b. wherein the combination of said composition and said propellant has a chemical heat of combustion not exceeding 20 kJ/g; c. wherein the aerosol device has a spray distance of 15 cm or greater; and d. wherein the aerosol device does not ignite at a distance of 15 cm between a burner flame and the actuator.
 10. The aerosol device of claim 9; wherein the plastic aerosol container has a capacity greater than 4 ounces.
 11. The aerosol device of claim 9; wherein the plastic aerosol container has a capacity greater than 10 ounces.
 12. The aerosol device of claim 9; wherein the aqueous composition comprises greater than 5% water.
 13. The aerosol device of claim 9; wherein the aqueous composition comprises greater than 50% water.
 14. The aerosol device of claim 9; wherein the pressure inside the plastic aerosol container is greater than 25 psi at 70° F.
 15. The aerosol device of claim 9; wherein the pressure inside the plastic aerosol container is greater than 50 psi at 70° F.
 16. The aerosol device of claim 9; wherein the pressure inside the plastic aerosol container is greater than 75 psi at 70° F.
 17. The aerosol device of claim 9; wherein the propellant comprises a hydrocarbon.
 18. The aerosol device of claim 9; wherein the propellant comprises an alkyl ether.
 19. An aerosol device comprising: a. a plastic aerosol container having an actuator, a valve, and containing an aerosol product composition comprising: ii. an aerosol composition; iii. a flammable, liquefied gas propellant; b. wherein the plastic aerosol container has a minimum burst pressure of at least 210 psig; c. wherein the combination of said aerosol composition and said propellant has a chemical heat of combustion not exceeding 20 kJ/g; d. wherein the aerosol device has a spray distance of 15 cm or greater; and e. wherein the aerosol device does not ignite at a distance of 15 cm between a burner flame and the actuator.
 20. The aerosol device of claim 19, wherein the pressure inside the plastic aerosol container is no more than 150 psig at 130° F. 